(1) Field of the Invention
This invention relates to dyeing finished textiles containing cellulose.
(2) Description of the Prior Art
Treatments for fabrics composed of cellulose and mixtures of cellulose with other polymers to render them wrinkle-resistant and durable-press, or self-smoothing on laundering, consist of applying and reacting a finishing agent on cellulose. These treatments form crosslinks or bonds between the linear cellulose molecules of which the fiber is composed. These finishing agents, or crosslinking agents, are typically made from the reaction of formaldehyde with polyamide to make a polyfunctional methylolamide or hydroxymethylamide. These methylolamides are applied from water and, after drying, react readily with cellulose under the influence of mild catalysts. Because they have more than one reactive methylolamide group, they form bridges, or crosslinks, between the linear cellulose molecules.
These crosslinking treatments do increase the wrinkle resistance and durable-press properties of the cellulosic fabric but also decrease the ability of the fiber to absorb moisture. This is shown by a lower moisture content of fabric when exposed to atmospheric moisture. The decreased absorptivity is also manifested in a decreased ability to absorb and retain dyes. The dyeability of the fabric is reduced to such an extent that, when a colored fabric is desired, the fabric must be dyed before the crosslinking treatment and therefore, before the manufacture of a garment or other textile article from the fabric. The choice of color in the textile then is restricted to those colors selected before the fabric is treated.
It has been possible to crosslink cellulosic fibers for wrinkle-resistance and durable-press with less restriction of absorptivity and dyeability, but the methods used are impractical for manufacturing commercial textiles. An example of such a method is described by Reeves, Perkins and Chance, Textile Research Journal vol. 30, pp. 179-192 (1960), which employs crosslinking while the fabric remains wet with the solution of crosslinking agent. This process is impractical because it requires a long reaction time in the presence of a strongly acidic catalyst. Another method described by Pierce, Frick and Reid, Textile Research Journal vol. 34, pp. 552-558 (1964), employs a standard process with inert components to inhibit deswelling on drying. This method is also impractical because large amounts of expensive materials are needed for the inert component.
Frick and Harper, Textile Research Journal vol. 51, pp. 601-606 (1981) disclose adducts of glyoxal and amides which are used as finishing agents for cotton solely as a means of eliminating formaldehyde fumes from the agent.